1. Field of the Invention
This invention relates generally to apparatus for recording and reproducing a video signal, and more particularly, to a video signal recording and reproducing apparatus for recording a video signal on a disc with a spiral record track thereon and reproducing a video signal from a disc on which the video signal is recorded in a spiral record track.
2. Description of the Prior Art
There has been proposed a disc available for inscribing which has a spiral groove preformed on a recording surface thereof so as to be traced for tracking operation on the occasion of recording and on which an information signal can be recorded once in a spiral record track along the spiral groove. This disc available for inscribing can be used for recording a video signal thereon in an editing manner, for example, by a video signal recording apparatus. In such recording of the video signal on the disc available for inscribing in the editing manner, the disc loaded on the video signal recording apparatus is rotated at, for example, constant angular velocity and each segment of, for example, one field or frame period of the video signal is recorded in each turn of the spiral record track on the rotating disc successively with at least one intermission in which the disc may be unloaded from the video signal recording apparatus once and then reloaded thereon.
When a certain video signal is recorded on the disc available for inscribing in the editing manner as mentioned above by a previously proposed video signal recording apparatus, there may be caused phase differences between a horizontal synchronous signal in each segment of one field or frame period of the video signal recorded in a part of the spiral record track formed before the disc is unloaded in the intermission and a horizontal synchronous signal in each segment of one field and frame period of the video signal recorded in another part of the spiral record track formed after the disc is reloaded in the intermission due to, for example, eccentricity of the disc even though the rotation of the disc is controlled to be synchronized with a vertical synchronous signal (a field or frame synchronous signal) of the video signal being to be recorded, so that an arrangement of the horizontal synchronous signals recorded on the respective turns of the spiral record track in the direction of the radius of the disc, namely, a horizontal period alignment (H alignment) is not established properly.
In connection with this, when the video signal which is recorded on the disc with such phase differences in the horizontal synchronous signals as mentioned above and an improper horizontal period alignment is reproduced from the disc, there results undesirable jumping of the horizontal synchronous signal in the video signal reproduced from the junction area between a portion of the disc on which a part of the spiral record track is formed before the disc is unloaded and a portion of the disc on which another part of the spiral record track is formed after the disc is reloaded. Moreover, substantial crosstalk interference by the horizontal synchronous signals between two adjacent turns of the spiral record tracks, one of which is formed before the disc is unloaded and the other of which is formed after the disc is reloaded, is caused.